1. Field of the Invention
This invention concerns dishwashers and more particularly venting arrangements for allowing the hot moist air generated during the drying cycle of the dishwasher to be vented into the surrounding room air.
2. Description of the Prior Art
Vent openings entering into the interior cabinet space of the dishwashing appliances are often required in order to allow escape of the hot humid air generated within the dishwasher interior and the entrance of relatively dry room air. Such vent openings are often used in conjunction with the drying operation of the dishwasher, particularly in convection type drying in which a heating element located at the bottom of the dishwasher tub heats the interior space, setting up convection currents within the dishwasher interior which ultimately displaces air into the surrounding room air. Such vented hot humid air passing into the much cooler air of the surrounding room space creates a steamy appearance and also condenses moisture on the adjacent surfaces. For this reason, the humid air from within the cabinet dishwasher interior is mixed with heated room air so as to reduce the relative humidity of the air ultimately passed out of the dishwasher via the vent opening. Even though such vented air is reduced in relative humidity, condensation problems still arise on the surfaces about the vent exit opening in immediate proximity to the exterior of the dishwasher. This is particularly aggravated in convection type dishwasher drying arrangements since relatively large openings located within the dishwasher door at the uppermost region are utilized to be most effective in creating efficient convection circulation. Such a large, prominently positioned opening must be suitably treated aesthetically, i.e., a grill or rib structure disposed within the opening which will also serve to prevent the entrance of fingers, objects, etc. from the opening. The presence of such a grill or rib structure within the opening creates relatively large surface areas at the point immediately proximate to the exterior of the dishwasher through which the vent air must pass.
Condensation occurs upon the hot humid air coming into contact with cooler surfaces such as to cool the air to the point where precipitation of the moisture occurs. The presence of condensate is undesirable in appearance and also tends to drip onto the floor immediately in front of the dishwasher, particularly upon opening of the dishwasher door. Such condensation on cooler surfaces is, of course, fundamentally a heat transfer phenomena, the surfaces cooling the hot humid air by conduction. Such conduction of heat and precipitation of moisture is increased with the increasing volume of high temperature and humid air coming into contact with the cooler surfaces. Furthermore, the capacity for the surfaces to act as a cooling heat sink depends on their ability to store large amounts of heat and to conduct the absorbed heat into the surrounding contiguous structures, such as to have the capacity for condensing relatively large quantities of water.
These conditions are met by the rib surfaces and also those exterior surfaces adjacent the upper edges of the vent exit opening since large volumes of the hottest air tends to curl about these exterior surfaces potentially producing considerable condensation.
It is, therefore, an object of the present invention to provide means for minimizing the formation of condensate on vent exit ribs disposed in the vent opening and also along the surfaces adjacent the vent exit opening.
It is another object of the present invention to provide a vent exit rib configuration by which any slight condensation which does form is retained within the interior of the dishwasher, to preclude the escape of the condensate onto the exterior surfaces of the dishwasher or being spilled onto the surrounding floor area.